Book Image

Bash Cookbook

By : Ron Brash, Ganesh Sanjiv Naik
Book Image

Bash Cookbook

By: Ron Brash, Ganesh Sanjiv Naik

Overview of this book

In Linux, one of the most commonly used and most powerful tools is the Bash shell. With its collection of engaging recipes, Bash Cookbook takes you through a series of exercises designed to teach you how to effectively use the Bash shell in order to create and execute your own scripts. The book starts by introducing you to the basics of using the Bash shell, also teaching you the fundamentals of generating any input from a command. With the help of a number of exercises, you will get to grips with the automation of daily tasks for sysadmins and power users. Once you have a hands-on understanding of the subject, you will move on to exploring more advanced projects that can solve real-world problems comprehensively on a Linux system. In addition to this, you will discover projects such as creating an application with a menu, beginning scripts on startup, parsing and displaying human-readable information, and executing remote commands with authentication using self-generated Secure Shell (SSH) keys. By the end of this book, you will have gained significant experience of solving real-world problems, from automating routine tasks to managing your systems and creating your own scripts.
Table of Contents (15 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

Creating users and groups systematically


In this section, we are going to learn how to create users and groups through a shell script.

 

How to do it...

Now, we will create a script to add a user. The useradd command is used to create a user. We are going to use the while loop, which will read our .csv file, and we will use the for loop to add each user that's present in that .csv file.

Create a script using add_user.sh:

#!/bin/bash
#set -x
MY_INPUT='/home/mansijoshi/Desktop'
declare -a SURNAME
declare -a NAME
declare -a USERNAME
declare -a DEPARTMENT
declare -a PASSWORD
while IFS=, read -r COL1 COL2 COL3 COL4 COL5 TRASH;
do
    SURNAME+=("$COL1")
    NAME+=("$COL2")
    USERNAME+=("$COL3")
    DEPARTMENT+=("$COL4")
    PASSWORD+=("$COL5")
done <"$MY_INPUT"
for index in "${!USERNAME[@]}"; do
    useradd -g "${DEPARTMENT[$index]}" -d "/home/${USERNAME[$index]}" -s /bin/bash -p "$(echo "${PASSWORD[$index]}" | openssl passwd -1 -stdin)" "${USERNAME[$index]}"
done

How it works...

In this recipe...